Pictures, both photographs and paintings, have often been changed with paint, particularly in the era before digital manipulation made the retouching of photographs far easier. Although editing has the potential to improve a picture, for photographs, it usually contrasts badly with the flat, glossy surface of the print. Many photos that have been edited are in need of special recovery techniques to restore them to their original condition. This can be done both digitally and with the use of special chemicals.
Scan the photo into a computer. Using a digital scanner, capture a high-quality image of the print and save it to a computer. For best results, attempt to capture the image at the highest resolution possible. Save the file as a .jpg or other high-quality image format.
Load the file into a photo editing program. There are a number of image manipulation programs that can be used to change the look of a photo. One of the most popular is Photoshop, made by Adobe, but another, similar program will suffice.
Edit the photo. This is the tricky part. Using the program's tools, attempt to remove the painted sections from the photo and "re-draw" the missing content. This can involve a bit of guesswork, as the sections that have been painted over have been obscured. In Photoshop, use the "blur," "sharpen," "smudge" and "clone stamp" tools. If you have another copy of the photo or a negative, use that as a guide.
Print out the corrected edition. Once you've re-edited the photo, save it and print out a new copy. This will require a high-quality printer, as well as the paper on which you want the photo to be printed. Or consider preserving the touched-up photo in a digital format.
Try out various paint removers. Before applying a paint remover to the photo, you want to make sure it won't damage the photo itself. To do this, test out one or more types of liquid paint removers by daubing a wet Q-Tip on a tiny corner of the photo or on a photograph printed on similar material. Observe the effect.
Gently brush the paint remover to the damaged section. Once you've found a proper paint remover, use it to gently brush away the paint on the photo. With luck, the original photograph should be preserved underneath.
Load the photo into a scanner to correct for errors. These two approaches can, of course, be used in combination with each other.